Who is Queen from Collected Stories and what is their importance?

Queen is the nickname that Jose the bartender gives to his prostitute friend who comes in every day to get a free meal in "The Woman Who Came at Six O'Clock." One day, Queen comes in at 6 p.m. and asks Jose to tell anyone who asks that she has been there since 5:45 p.m. He agrees but she will not tell him the reason; she has murdered one of her clients and wants an alibi to give her time to escape to another town.